Eyes can be used to convey and express emotion. However, it can be challenging to capture aspects of the eye region, including an eyelid, in three-dimensional (3D) modeling. Specifically, it can be difficult to produce an accurate 3D representation of an eyelid. Digital representations or digital doubles of a subject can be used in, for example, movies and video games.
FIG. 1 illustrates an example of human eyelids. As shown in FIG. 1, a subject 100, such as an actor, has two upper eyelids 110 and two lower eyelids 120 in their eye region. In order to create a digital representation of, for example, an actor's eyelid, an expressive performance of the actor's eye region is obtained. An expressive performance can include a series of movements representing a facial expression and can represent a subject smiling, laughing or blinking. An expressive performance can capture a subject's facial expression for a particular period of time, such as a few seconds or a few minutes. An expressive performance can include various aspects of the eye region that can be used to create a digital representation of the eye region.
However, in an expressive performance, an eyelid can undergo deformation and wrinkling. The skin on the eyelid rolls and folds inward when the eye opens, and stretches over the eyeball when the eye is shut. Due to concavities and eyelashes, this can result in significant self-shadowing, inter-reflections, and partial occlusions. In some facial expressions a significant part of the eyelid is folded in and not visible at all. A labor intensive manual process may be used to create digital representations of eyelids.